I'm clutching at straws a little here but was wondering if anyone had any insight into whether this was possible. It doesn't seem as though Amazon provide any kind of [public] API for getting data about a users kindle books and specifically how far through them they have read, but I'm hoping I've missed something.
So basically, given a users amazon login or kindle email address or some other unique identifier I would like to be able to connect to a web service to get back the list of kindle books the user has purchased/downloaded and then determine how far through them they have read. Amazon must have this data in order to be able to sync books across devices, but it doesn't appear that they have made available an API to get this data.